Control mechanisms



May 1965 J. E. B. JACOB ETAL CONTROL MECHANISMS Filed Aug. 1, 1963 FIG.1

FIG.2

United States Patent 3,181,467 CONTROL MECHANISMS John Edmund Baldwin Jacob and James McGregor Sowerby, Hitchin, England, assignors to British Aircraft Corporation Limited, London, England, a British company Filed Aug. 1, 1963, Ser. No. 299,265 Claims priority, application Great Britain, Aug. 3, 1962, 29,854/ 62 8 Claims. ((31. 102-83) This invention relates to control mechanisms of the time-delay type.

A control mechanism according to this invention includes a rotatable member having. one or more projections, and an arresting member arranged for'movement in response to an actuating force of a predetermined value from a first position in which, when the rotatable member is rotated in one direction, the arresting member will engage the projection, or one of the projections, so as to arrest the rotatable member, to a second portion in which the arresting member is clear of the projection or projections, the arresting member being arranged also to return from the second position to the first position if the actuating force is reduced below its predetermined value, and the mechanism being arranged so that the arresting member then locks the rotatable member permanently against further rotation in the same direction.

A control mechanism of the time-delay type according to the invention, for controlling the arming operation in a guided missile, will now be described by way of example and with reference to the accompanying partlydiagrammatic drawings, of which:

FIGURE 1 is a sectional end view of the mechanism taken on the line II of FIGURE 2; FIGURE 2 is a section taken on the line IIII of FIGURE 1; and,

FIGURE 3 is a detail view in the direction of the arrow III in FIGURE 1. 1

The missile has a warhead (see FIGURE 2), to the rear end of which a support block 11 is secured by means of a locking ring 12; the ring 12 is screwed into the support block 11 and abuts against a ring 10a formed circumferentially on the warhead, so asto hold the ring 19a against a shoulder 11a in the block. .The block 11 has a spigot portion 11b formed adjacent its front end, and the open end of a cylindrical casing 13, having its other end 13a closed, engages the spigot portion 11b and is secured to the block 11 by means not shown.

A cartridge 14 is located in the block 11 behind the warhead 10; and an igniter 15 is located, co-axially behind the cartridge 14, in a further support block 11c which is secured by screws lid to the support block 11. The igniter 15 is arranged to be operated electrically by a crush switch (not shown) on the front of the warhead, and is separated from the cartridge 14 by a rotatable disc 16 mounted on the support block 11. V

The disc 16 is arranged to be rotated at a constant speed in the direction shown in FIGURE 1, through a pinion 17 and a gear ring 18 attached to the,disc 16, by an escapement-controlled clockwork mechanism housed within the block 11 but not shown in the drawings.

' In the position shown in the drawings, the disc 16 is restrained from rotation by a plunger 19 engaging a notch 16a on the circumference of the disc. The plunger 19 is ice movable, upwardly as seen in FIGURE 2, by an explosive device (not shown) which is arranged to be operated electrically at a convenient time, for example at the moment of firing the missile, so as to initiate rotation of the disc.

A catch 20 on the circumference of the disc 16 is arranged for engagement with a fixed stop 21, to bring the disc to rest at the desired position at the end of its rotation, in which position the catch 20 also engages a spring locking pawl 22 fixed to the block 11, so as to prevent rotation of the disc in the reverse direction. A detonator 23 is set in the disc in such a position that when the catch 20 is engaging the stop 21, the detonator 23 lies immediately between and adjacent to the igniter 15 and cartridge 14.

In operation, on the firing of the explosive device which frees the plunger 19 from the notch 16a, the disc 16 is free to rotate, and the clockwork mechanism may then rotate the disc for a predetermined time through part of one revolution, after which the clockwork is so arranged that it causes the disc to move as quickly as possible into the position in which the catch 20 engages the stop 21. This position of the mechanism will be referred to herein as the armed position, while the position shown in the drawings will be called the normal position. The predetermined time of rotation mentioned above may have any appropriate value: in a typical case it is 2 /2 seconds. With the mechanism in the armed position, when operation of the crush switch causes the igniter 15 to be fired, for example by impact of the missile with a body, the igniter ignites the detonator 23, which in turn detonates the cartridge 14 so as to cause the warhead 10 to explode.

On the circumference of the disc 16 are a number of cut-away portions 24, which define between them six generally-similar projections or catches 25, each of which consists of a leading portion 25a and a trailing portion 25b which projects from the disc further than the leading portion. In the block 11 and parallel to the axis of rotation of the disc is mounted a hollow cylindrical housing 26. The end of the housing 26 nearest the disc 16 carries a forward stop block 27 having an axial hole formed therein. An acceleration-sensitive plunger 23 is mounted so as to befree to move axially in the housing 26 and block 27, and is biased towards the position shown in FIGURE 2 by a compression spring 29 acting between the block 27 and a ring 30 secured to the plunger 28. The plunger 28 has a head 31, shown in FIGURE 3, comprising a block portion 310 and a projecting portion 31b. The head 31 is preventedfrom rotating by two stops 27a on the block 27. The plunger 28 is positioned so that, with the mech anism in the normal position, the edge of the disc 16 is level with the head, and the projection 31b lies behind the disc, as shown in FIGURE 3. Moreover the plunger 28 is aligned with the direction of flight of the missile, the end of the plunger carrying the head 31 being the rear end.

When the missile is subjected to a forward acceleration greater than a predetermined value in the direction of its line of flight (as indicated by the arrow in FIGURE 2), the plunger 28 tends to move in the opposite direction to the missile against the action of spring 29. If the disc 16 is now rotating, so that the head 31 of the plunger comes opposite a cut-out portion 24 of the disc, the head will move clear of the disc to the position shown by the broken lines in FIGURE 3, thus allowing the disc to continue to rotate until the machanism is in the armed position, provided that the acceleration of the missile is maintained above the predetermined value.

If, however, the acceleration fall below this value for any reason after the plunger has moved clear of the disc, the spring 29 moves the plunger 28 back again so that the trailing portion 25b of a catch 25 strikes the block portion 31a of the head 31 of the plunger, thus arresting the disc. The leading portion 25a ot the catch lies in the position shown in FIGURE 3 relative to the head 31, so that the projection 31b prevents the plunger head 'from moving free of the disc again even if the acceleration is increased once more above the previously-mentioned predetermined value. The clockwork which operates the disc 16 prevents the disc rotating in reverse, so that the whole mechanism is now locked in an inherently safe position intermediate the norma and armed positions, so that the missile cannot thereafter become armed.

In the event of the plunger 28 retracting just too late for the projection 31b to pass between two catches, that is to say if the projection 31b hits a catch 25, the disc 16 will still continue to rotate and the plunger head will engage the next catch instead so: as to stop the disc.

There is a slight possibility that after the disc has begun to rotate and before the missile is armed, the plunger 28 may be set into vibration which causes it to oscillate back and forth along its axis so that its head 31 is clear of the disc 16 (in the position shown by broken lines in FIGURE 3) at some instants even though the acceleration of the missile is less than the predetermined amount required to maintain the plunger in that position. This could for example occur if the missile hit something while the disc was still rotating. To re duce the possibility of the missile becoming armed in this state, the spacing between the catches 25 is preferably irregular, and arranged so that under vibration conditions the head 31 of the plunger will hit one or other of the catches, whereupon both plunger and disc will be brought to a halt. It is thus arranged that the missile only becomes armed when subjected to a continuous acceleration above the predetermined value for the predetermined time.

The number of catches 25 need not be six but may be any convenient number, and the catches can be arranged to cooperate with any suitable device besides-- or instead o'f- -a plunger sensitive to acceleration such as that described herein. For instance, a solenoid-operated plunger having a head similar to the head 31 may be included in a safety circuit of the missile so as to engage a catch 25 in the event of failure of any component of the missile.

We claim:

1. A time-delay control mechanism for a missile having a warhead, the control mechanism comprising a rotatable disc member formed with a plurality of radial projections at intervals around its periphery, an arresting member eo-openable with the said radial projections, spring means urging the arresting member in one direction towards a first position and inertia means for moving the arresting member against the action of the spring means to a second position when the missile has a predetermined acceleration, the projections on the disc member each comprising a leading part and a trailing part which extends radially outwards beyond the leading part, and the arresting member being also in two parts, one of which overlaps and can engage only the trailing parts of the projections, and the other of which projects outwards to a greater extent and overlaps both parts of the projections.

2. A control mechanism comprising a rotatable member rotatable about a fixed axis and formed with a plurality of projections at intervals around the said axis, ro-

tary drive means for rotating the rotatable member about its axis in a given direction, an arresting member cooperable with the said projections, biasing means urging the arresting member in one direction towards a first position, and variable force-applying means for moving the arresting member against the action of the said biasing means to a second position, the projections on the rotatable member being engageable with the arresting member when the arresting member is in its first position, said projections and arresting member comprising interengaging means for preventing movement of the arresting member away from its first position once the arresting member has engaged any one of the projections, the inter-engagement of the arresting member with one of the projections being effective also in preventing further rotation of the rotatable member in the said given direc tion.

3. A control mechanism according to claim 2, in which the arresting member is urged by a spring towards the first position, and in which the means moving the arresting member towards its second position, against the action of the spring, comprise inertia means responsive to an ecceleration force during use.

4. A control mechanism according to claim 3 for a missile having a warhead, including a stop which the rotatable member must reach before the warhead can be ignited.

5. A control mechanism according to claim 3 for a missile having a warhead including, -a stop which the rotatable member must reach before the warhead can be ignited, the rotary drive means for the rotatable memher being a two-speed clockwork motor which rotates the rotatable member slowly at first and then quickly to the position in which the rotatable member engages the stop.

6. A control mechanism according to claim 2, in which the projections are at irregular intervals around the axis of the rotatable member.

7. A missile including a warhead and a time-delay control mechanism comprising a rotatable member rotatable about a fixed axis and formed with a plurality of projections at intervals around the said axis, rotary drive means for rotating the rotatable member about its axis in a given direction, means for igniting the warhead of the missile when the rotatable member reaches an armed position, an arresting member co-operable with the said projections, biasing means urging the arresting member in one direction towards .a first position, and variable force-applying means for moving the arresting member against the action of the said biasing means to a second position, the projections on the rotatable member being engageable with the arresting member when the arresting member is in its first position, the said projections and arresting member including inter-angaging means which act to prevent movement of the arresting member away from its first position once the arresting member ha engaged any one of the projections, the inter-engagement of the arresting member with one of the projections being effective also in preventing further rotation of the rotatable member in the said given direction towards the armed position.

8. A missile including a warhead and a time-delay control mechanism comprising a rotatable member rotatable about a fixed axis and formed with a plurality of projections at intervals around the said axis, rotary drive means for rotating the rotatable member about its axis in a given direction, means for igniting the warhead of the missile when the rotatable member reaches an armed position, an arresting member co -operable with the said projections, biasing means for urging the arresting member in one direction towards a first position, in which the arresting member i engageable with the projections, and inertia means for moving the arresting member against the action of the said biasing means to a second position, in which the arresting member is clear of engagement with the projections, the said projections and arresting member including inter-engaging means which act to prevent movement of the arresting member away from its first position once the arresting member has engaged any one of the projections, the inter-engagement of the arresting member with one of the projections being eifeotiva also in preventing further rotation of the rotatable member in the said given direction towards the armed position.

References Cited by the Examiner UNITED STATES PATENTS 2,897,760 8/59 Mott-Smith 102-80 2,948,219 8/60 Sap'p 102-78 3,059,577 10/62 Hutchison et a1 10278 X SAMUEL FEINBERG, Primary Examiner. SAM ENGLE, Examiner. 

2. A CONTROL MECHANISM COMPRISING A ROTATABLE MEMBER ROTATABLE ABOUT A FIXED AXIS AND FORMED WITH A PLURALITY OF PROJECTIONS AT INTERVALS AROUND THE SAID AXIS, ROTARY DRIVE MEANS FOR ROTATING THE ROTATABLE MEMBER ABOUT ITS AXIS IS GIVEN DIRECTION, AN ARRESTING MEMBER COOPERABLE WITH THE SAID PROJECTIONS, BIASING MEANS URGING THE ARRESTING MEMBER IN ONE DIRECTION TOWARDS A FIRST POSITION, AND VARIABLE FORCE-APPLYING MEANS FOR MOVING THE ARRESTING MEMBER AGAINST THE ACTION OF THE SAID BIASING MEANS TO A SECOND POSITION, THE PROJECTIONS ON THE ROTATABLE MEMBER BEING ENGAGEABLE WITH THE ARRESTING MEMBER WHEN THE ARRESTING MEMBER IS IN ITS FIRST POSITION, SAID PROJECTIONS AND ARRESTING MEMBER COMPRISING INTERENGAGING MEANS FOR PREVENTING MOVEMENT OF THE ARRESTING MEMBER AWAY FROM ITS FIRST POSITION ONCE THE ARRESTING MEMBER HAS ENGAGED ANY ONE OF THE PROJECTIONS, THE INTER-ENGAGEMENT OF THAT ARRESTING MEMBER WITH ONE OF THE PROJECTIONS BEING EFFECTIVE ALSO IN PREVENTING FURTHER ROTATION OF THE ROTATABLE MEMBER IN THE SAID GIVEN DIRECTION. 